1. Field of the Invention
The invention relates to a method for purification of .alpha.-olefins, in particular, ethylene or propylene, for polymerization use and a method for production of poly-.alpha.-olefins by use of such purified .alpha.-olefins.
2. Description of the Prior Art
.alpha.-Olefins, in particular, ethylene or propylene, are very useful for the production of widely used polymers, polyethylene or polypropylene. With regard to such an .alpha.-olefin for polymerization use, it is necessary that impurities contained therein are removed to purify the .alpha.-olefin before it is polymerized.
As one of such methods for purification of .alpha.-olefins, there is known a method in which, for instance, propylene which contains carbonyl sulfide as an impurity is contacted with an absorbent composed of nickel carried on a support material thereby to reduce the content of the carbonyl sulfide in the propylene, as is disclosed in Japanese Patent Application Laid-open No. 61-76425.
A further method is also known in which liquid propylene is contacted with metallic nickel at a temperature of 0-80.degree. C. thereby to remove carbonyl sulfide from the propylene together with carbon monoxide, as is disclosed in Japanese Patent Application Laid-open No. 5-70373.
On the other hand, there is also known a method in which a light oil fraction from thermal cracking of heavy oil is first treated with alumina, silica-alumina or, silica to remove impurities such as nitrogen or oxygen compounds, as is disclosed in Japanese Patent Application Laid-open No. 1-259089.